Lyme disease is caused by bacteria called
Borrelia burgdorferi
(
B. burgdorferi)
. Blacklegged ticks and other species of ticks can carry these bacteria. The ticks pick up the bacteria when they bite mice or deer that are infected with
B. burgdorferi
. You can get the disease if you are bitten by an infected tick.

Lyme disease was first reported in the United States in the town of Old Lyme, Connecticut, in 1977. The same disease occurs in many parts of Europe and Asia. In the United States, most Lyme disease infections occur in the following areas:

Northeastern states, from Virginia to Maine

North-central states, mostly in Wisconsin and Minnesota

West Coast, particularly northern California

There are 3 stages of Lyme disease.

Stage 1 is called early localized Lyme disease. The infection has not yet spread throughout the body.

Stage 2 is called early disseminated Lyme disease. The bacteria have begun to spread throughout the body.

Stage 3 is called late disseminated Lyme disease. The bacteria have spread throughout the body.

Risk factors for Lyme disease include:

Doing outside activities that increase tick exposure (for example, gardening, hunting, or hiking) in an area where Lyme disease is known to occur

Having a pet that may carry ticks home

Walking in high grasses

Important facts about tick bites and Lyme disease:

In most cases in the U.S., a tick must be attached to your body for 24 - 36 hours to spread the bacteria to your blood. Ticks that cause Lyme disease in Europe transmit the bacteria more quickly, within 24 hours.

Blacklegged ticks can be so small that they are almost impossible to see. Many people with Lyme disease never even see or feel a tick on their body.

There may be a "bull's eye" rash, a flat or slightly raised red spot at the site of the tick bite. Often there is a clear area in the center. It can be large and expanding in size. This rash is called erythema migrans. Without treatment, it can last 4 weeks or longer.

Symptoms may come and go. Untreated, Lyme disease can spread to the brain, heart, and joints.

Symptoms of early disseminated Lyme disease (Stage 2) may occur weeks to months after the tick bite and may include:

Numbness or pain in the nerve area

Paralysis or weakness in the muscles of the face

Heart problems, such as skipped heartbeats (palpitations), chest pain, or shortness of breath

Symptoms of late disseminated Lyme disease (Stage 3) can occur months or years after the infection. The most common symptoms are muscle and joint pain. Other symptoms may include:

A blood test can be done to check for antibodies to the bacteria that cause Lyme disease. The most commonly used is the ELISA for Lyme disease test. An immunoblot test is done to confirm ELISA results.

In areas where Lyme disease is more common, your health care provider may be able to diagnose early disseminated Lyme disease (Stage 1) without doing any lab tests. In the early stage of infection, blood tests can be normal.

If diagnosed in the early stages, Lyme disease can be cured with antibiotics. Without treatment, complications involving the joints, heart, and nervous system can occur. However, these symptoms and stages are still treatable and curable.

Rarely, a person will continue having symptoms that can interfere with daily life after they have been treated with antibiotics. Some people call this post-Lyme disease syndrome. The cause of this syndrome is unknown.

Symptoms that occur after antibiotic treatment for Lyme disease may not be signs of active infection and may not respond to antibiotic treatment.

Take precautions to avoid direct contact with ticks. Be extra careful during warmer months. Whenever possible:

Avoid wooded or bushy areas, or areas with high grasses and leaf litter.

Walk in the center of trails.

Check yourself and your pets frequently during and after your walk or hike.

When walking or hiking in wooded or grassy areas, spray all exposed skin and your clothing with insect repellant.

See also: Bug repellent safety

You may also treat clothing, such as boots, pants, and socks, with a product that contains permethrin. It remains protective for several washings.

Ticks that carry Lyme disease are so small that they are very hard to see. After returning home, remove your clothes and thoroughly inspect all skin surface areas, including your scalp. Shower soon after coming indoors to wash off any unseen ticks.

Review Date: 2/27/2012Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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